Cor is right, I do recommend that each L3 also have a L2 (preferably 3 L2 EVSE for each L3 EVSE), because the L3 reduces its charge current rate after 80%SOC to a L2 level to protect the EV's pack.. It is better for a driver to disconnect from the L3 after reaching 80%SOC and move over to a nearby L2 EVSE, so as to free-up the L3 for another driver. Depending on the state of the EV's pack, that last 20% can sometimes take longer than the time it took the L3 EVSE pump the pack up to 80%SOC.
Each L3 EVSE interface with the driver differently (different look and feel, and charge selections), but the charge current methodology is the same: reduces the charge current at the 80%SOC point. Depending on what EV you drive, and how far you need to go, depends on if you need to have a full-100%SOC before hitting the road again, or just use the fastest charging method off unplugging at 80%SOC and get back on the road again to the next EVSE/charge-point. I did this way back when (in the 1990's) when I used the first generation EVSE (Avcon's). With 6 on-board chargers, I could charge quickly my PbSO4 pack to 60%SOC before it started to taper its charging current). I found it faster and wiser to not fully-100%SOC charge each time I charged. I charged at the fast rate to the level I wanted, unplugged, and hit the road to the next charging point. This saved a lot of charging time. Even though my conversion was not today's state-of-the art Li-ion technology http://brucedp.150m.com/blazer/ I was able to use the then old-style EVSE infrastructure to drive a 320 mile round trip from Silicon Vally to Sacramento and back on 6 different occasions (I especially liked to do this when the friendly nedra.com folk were racing up in Sacramento). Like others, Cor has seen what I posted about this on the evdl, but I also share my knowledge/detail with cities that are considering an EVSE installation. This morning, the newswires were slow with few interesting pieces to prepare for posting, so I had the time to respond to one news item that announced a city is going to be installing a L3 EVSE. http://www.wdbj7.com/video/Roanoke-City-Council-to-vote-on-new-electric-car-charger/25331908 Posting my comments to the news piece usually does not get through to the right people making the decisions, and because in the video they stated the city council was going to vote on it come Monday (not much time), I spent the morning putting together an email and sent it out to that city's council members. Surprisingly, a couple of them responded thanking me for the info (most of the time, I get nada/squat for all my efforts, but persevere). I pointed out that the video had errors (an L2 EVSE was shown, yet the piece was about a L3 EVSE). In the video it mentioned that the $86k L3 being donated by a local clean cites org, and their rep stated on camera that they wanted to show it with high visibility. Those words bring a shiver down my spine, as too many EVSE installations were show-case, thus preformed completely wrong. After the one hour of media coverage and the people in-charge get their accolades, the drivers were stuck with EVSE that is just awful, or severely lacking because the driver was not considered when the installation was laid out. I explained that the location, signage, spot painting, and having EV laws on the city's books to punish violators (ice'd spots) was critical. I stressed the importance of EVSE locations should have 24/7 access in a well lit/safe location and that has to be something for the driver to do: restaurants, shopping, restrooms, etc. Lastly, I pointed out that their L3 installation at the city center may not be as good as at the nearby mall where 'everyone' wants to go. I further explained that it is now an established city-business model to entice plugin drivers to come spend money in a city while their EVs charge, as it is a win-win-win scenario: (driver gets a charge, local businesses profit, and city tax revenue from those profits + use-fees cover EVSE costs). ... As a side note, there are actually several different companies selling L3 EVSE and some offer at different power output levels. The lower power output models not only cost less, but cost less for the electrical grid power installation. However a lower powered L3 takes longer to recharge the EV. This can be a good thing for local businesses, as the driver is awhile longer than just 20 minutes to spend money. A ~20 minute to 80%SOC L3 EVSE is generally a 50kW unit. But a lower cost 20KW L3 EVSE would be easier to implement, and have the driver stick around for ~50 minutes. So far, no one in this area has gone that route, as all the L3 EVSE installation around here is the 50kW variety. Cor and I are in the SF bay area where the majority of the existing L3 EVSE former Blink/Ecotality (now taken-over/swallowed-up by CarCharging Group ccg), see http://www.afdc.energy.gov/locator/stations/results?utf8=%E2%9C%93&location=94303&filtered=true&fuel=ELEC&owner=all&payment=all&ev_dc_fast=true&radius=true&radius_miles=50 The Blink L3 EVSE is a curious beast when compared to other L3 EVSE. It has two couplers but only one will power at a time. Yet, having two couplers on 1 L3 EVSE does allow charge queuing to occur much more simply. The EV that wants a L3 charge comes up to the Blink L3 EVSE which has 2 spots allocated for it, and may already have 1 EV charging. The second EV plugs in and waits as when the first EV is done, the second coupler turns on. But sadly, these L3 EVSE are listed as having two EVSE, when really it can only charge one at a time. Some of the other EVSE are so spartan in their communication, it makes it harder to know what is going on, or what to expect (should I go for a coffee or stay?). Whereas the Blink L3 EVSE gives lots of screen info (maybe too much?). I use the above URL as only one of several tools to know what EVSE is available. I also use plugshare.com (which is also owned by recargo. BTW recently recargo has made an effort to synchronize some of the data between recargo and plugshare, but recargo's user interface is more app oriented, whereas plugshare has a more friendly site interface). There are several other EVSE finder sites/apps, but those two (above) are the major players. It is good for drivers to familiarize themselves with other EVSE finder methods, as occasionally, these 'tools' will become unavailable from time to time (site down, sever failure, etc.). Then, it is good to have a back-up method to find the EVSE you need. Looking at the URL above again, notice how clustered the L3 are: too many together, much closer that every 50 miles. And now look at what L3 is available in the news item's region: http://www.afdc.energy.gov/locator/stations/results?utf8=%E2%9C%93&location=Roanoke%2C+VA&filtered=true&fuel=ELEC&owner=all&payment=all&ev_dc_fast=true&radius=true&radius_miles=150 The nearest L3 EVSE is 86 miles away. I mentioned I thought it was funny that the city's local Nissan Dealership did not already have an L3 EVSE installed. It is feast, or famine: too many in the Silicon Valley, CA area as all Hi-Tech/Bio-Medical companies worth their salt want to have L3 EVSE at their work sites to keep their talent from walking (like handing out candy to the techies to keep them around). And in other parts of the U.S., huge voids of public EVSE. {brucedp.150m.com} - On Sat, Apr 5, 2014, at 04:38 PM, Cor van de Water wrote: > It is simply to protect the battery that charging throttles back > somewhere around the 80% mark > from fast-charging to lower speed. > That is why Bruce has recommended that a Fast (level 3) charger always be > accompanied by a level 2, > so that someone who needs to top up to above 80% can first do a fast > charge to 80% and then > free up the fast charger for the next fast-charging vehicle, while being > topped up at the lower speed > of the level 2, since the charging speed above 80% is not dependent on > what the charger can deliver as much as on > what the battery can take without damage. > What typically happens is that around that 80% point, the voltage of the > cells will rise enough > that the charging algorithm transitions from being current limited (how > much can the charger deliver to the battery) > to voltage limited (what max voltage is allowable for the cell) and the > current will correspondingly fall off over time > while the cell is going from 80-ish to 100%, so it is an area of > diminished returns: you got to wait longer for every > next percent added above 80% charge, so that is why it only makes sense > to fast-charge to 80%. >- > > -----Original Message----- > From: [email protected] on behalf of Martin Winlow > Sent: Sat 4/5/2014 3:33 PM > To: Robert Gienger; Electric Vehicle Discussion List > Subject: Re: [EVDL] CHAdeMO DC Charge time? > Hi Bob, I can only offer you the dubious benefit of my UK experience > using a chademo on my i-Miev... At zero charge state on the car the > chademo says it is supplying ~120A @ 330V. The charge power does > gradually reduce until at 80% full, the currant has fallen to about 20A @ > 330V and automatically the charging stops. If you re-start the chademo, > it will continue up to 100% but I don't know if the currant stays at 20A > or what (forgot to look!). MW > - > > > > On 5 Apr 2014, at 23:21, Robert Gienger <[email protected]> wrote: > > Occasionally I charge at Premiere Nissan in San Jose, CA. When using the > > CHAdeMO DC fast charger, I noticed it charges very fast up to 80% and > > then slows down to a trickle. Am I correct or is this just my imagination? > > Is it faster to top off with a 220v level 2 unit? > > Thanks, Bob Gienger - -- http://www.fastmail.fm - Accessible with your email software or over the web _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
